Costello J, Njue A, Lyall M, Heyes A, Mahler N, Philbin M, Nazareth T. Efficacy, safety, and quality-of-life of treatments for acute relapses of multiple sclerosis: results from a literature review of randomized controlled trials. Degener Neurol Neuromuscul Dis. 2019 Jul 1;9:55-78. doi: 10.2147/DNND.S208815
Walker EA, Picker MJ, Granger AL, Dykstra LA. Effects of opioids in morphine-treated pigeons trained to discriminate among morphine, the low-efficacy agonist nalbuphine, and saline. J Pharmacol Exp Ther. 2004 Jul;310(1):150-8.
Allen RM, Granger AL, Dykstra LA. The competitive N-methyl-D-aspartate receptor antagonist (-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid (LY235959) potentiates the antinociceptive effects of opioids that vary in efficacy at the mu-opioid receptor. J Pharmacol Exp Ther. 2003 Nov 1;307(2):785-92.
Allen RM, Granger AL, Dykstra LA. Dextromethorphan potentiates the antinociceptive effects of morphine and the delta-opioid agonist SNC80 in squirrel monkeys. J Pharmacol Exp Ther. 2002 Feb 1;300(2):435-41.